Timing detection device and timing detection method

Abstract

The timing detection device (52) includes a main reference code generation module (525), an auxiliary reference code generation module (526), a first correlation processing module (521), a second correlation processing module (522), and a subtraction module (523). The main reference code generation module (525) generates a main reference code (C51) consisting of the same code for synchronization included in a received signal. Using a portion of the same code as the code for synchronization, the auxiliary reference code generation module (526) generates an auxiliary reference code (C52; C52A; C52B; C52C) consisting of a code configuration different from the main reference code (C51) and without generating a main lobe during correlation processing. The first correlation processing module (521) correlates the received signal with the main reference code (C51) and outputs a first correlation result. The second correlation processing module (522) correlates the received signal with the auxiliary reference code (C52; C52A; C52B; C52C) and outputs a second correlation result. The subtraction module (523) subtracts the first correlation result from the second correlation result.

Description

TECHNICAL FIELD

[0001] The present disclosure generally relates to time detection techniques and more particularly relates to devices and methods for detecting timing upon receiving a digitally modulated signal.BACKGROUND OF THE INVENTION

[0002] A Japanese patent document, JP 2005311532 A, titled "Radio communication method and device", describes a wireless communication method and apparatus for receiving a signal modulated with a barker code.

[0003] Document EP 3 683 970 Al discloses an ultra-wideband ("UWB") communication system comprising a pair of UWB transceivers, methods for securely performing channel sounding. In a first GCP Sync method, a pre-determined set of Golay Complementary Pairs is added to an 802.15.4a frame. In a second CLASS method, a cyphered low auto-correlation sum set is added to frame. In a third LCSSS method, a low cross-correlation sidelobe sum set is added to the frame. In general, these methods are adapted to transmit a pseudo-randomly generated codeset which may have inherent sidelobe distortions, and then, in the receiver, to compensate for this, and any channel-induced, distortion by selectively modifing the cross-correlation codeset.

[0004] However, in the above prior art, when the correlation is performed using a spread code such as a conventional barker code and a predetermined timing such as a slot timing is detected, a relatively large side lobe occurs in the correlation result. This may cause an error in the detected timing.

[0005] Therefore, a need exists to suppress the side lobe during correlation processing.SUMMARY OF THE INVENTION

[0006] The invention is defined by the appended claims. The timing detection device according to the present disclosure includes a main reference code generation module, an auxiliary reference code generation module, a first correlation processing module, a second correlation processing module, and a subtraction module. The main reference code generation module is configured to generate a main reference code consisting of the same code as a code for synchronization included in a received signal. The auxiliary reference code generation module, by using a portion of the same code as the code for synchronization, is configured to generate an auxiliary reference code consisting of a code configuration different from the main reference code and suppressing the generation of a main lobe during a correlation process. The first correlation processing module is configured to output a first correlation result by correlating the received signal with the main reference code. The second correlation processing module is configured to output a second correlation result by correlating the received signal with the auxiliary reference code. The subtraction module is configured to subtract the first correlation result from the second correlation result.

[0007] In this configuration, the side lobe of the first correlation result and the side lobe of the second correlation result are offset in the output of the subtraction module.EFFECT(S) OF THE INVENTION

[0008] According to the invention, the sidelobe during correlation processing can be suppressed.BRIEF DESCRIPTION OF THE DRAWINGS

[0009] FIG. 1 illustrates a functional block diagram of a timing detection device, in accordance with an embodiment of the present disclosure; FIG. 2 illustrates a functional block diagram of an Automatic Identification System (AIS) for a ship, in accordance with an embodiment of the present disclosure; FIG. 3 illustrates an example data configuration of a signal for the AIS, in accordance with an embodiment of the present disclosure; FIG. 4 illustrates a bit array of Syncword (SW) data, in accordance with an embodiment of the present disclosure; FIG. 5A illustrates an example of a bit arrangement of a main reference code, in accordance with a first embodiment of the present disclosure; FIG. 5B is a diagram showing an example of a bit arrangement of an auxiliary reference code, in accordance with the first embodiment of the present disclosure; FIG. 6A and FIG. 6B are diagrams showing the correlation result (first correlation result) between SW data and the main reference code, in accordance with the first embodiment of the present disclosure; FIG. 6C and FIG. 6D are diagrams showing the correlation result (second correlation result) between the SW data and the auxiliary reference code, in accordance with the first embodiment of the present disclosure; FIG. 7 is a diagram showing the final correlation result (final correlation data), in accordance with the first embodiment of the present disclosure; FIG. 8 is a flowchart showing an example of a timing detection method, in accordance with an embodiment of the present disclosure; FIG. 9A shows an example of a bit arrangement of the main reference code, in accordance with a second embodiment of the present disclosure; FIG. 9B shows an example of a bit arrangement of the auxiliary reference code, in accordance with the second embodiment of the present disclosure; FIG. 10A and FIG. 10B show the correlation result (second correlation result) between the SW data and the auxiliary reference code, in accordance with the second embodiment of the present disclosure; FIG. 11A shows an example of a bit arrangement of the main reference code according to a third embodiment, in accordance with a third embodiment of the present disclosure; FIG. 11B shows an example of a bit arrangement of the auxiliary reference code according to the third embodiment, in accordance with the third embodiment of the present disclosure; FIG. 12 shows the final correlation result (final correlation data), in accordance with the third embodiment of the present disclosure; FIG. 13A shows an example of a bit arrangement of the main reference code, in accordance with a fourth embodiment of the present disclosure; FIG. 13B shows an example of a bit arrangement of the auxiliary reference code, in accordance with the fourth embodiment of the present disclosure; and FIG. 14 shows the final correlation result (final correlation data), in accordance with the fourth embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION (Embodiment 1)

[0010] A timing detection technique according to a first embodiment of the present invention will be described with reference to the figures. FIG. 1 is a functional block diagram of a timing detection device 52 (hereinafter also interchangeably referred to as a "correlation module 52") according to an embodiment of the present invention. FIG. 2 is a functional block diagram of the AIS device according to the embodiment of the present invention.(Configuration of Automatic Identification System [AIS] Device)

[0011] FIG. 2 is a functional block diagram of the AIS device 10 according to an embodiment of the present invention. As shown in FIG. 2, the AIS device 10 includes an antenna 20, a first down conversion module 30, a coarse frequency control module 41, a symbol timing detection module 42, a second down conversion module 43, a phase control module 44, a frequency tracking module 45, a signal detection module 51, a correlation module 52, and a decoding module 60. The modules of the AIS device 10 except the antenna 20 can be realized by an analog circuit, a digital circuit, an arithmetic processing unit such as a computer, etc.

[0012] The antenna 20 receives the signal for an AIS and outputs the received signal to the first down conversion module 30. The first down conversion module 30 down-converts the received signal to a frequency (for example, 10 times the frequency) that is a predetermined multiple of the baseband signal. The first down conversion module 30 outputs the down-converted received signal to the coarse frequency control module 41 and the signal detection module 51.

[0013] FIG. 3 illustrates an example data configuration of a signal for the AIS 10 for the ship, in accordance with an embodiment of the present invention. The signal for automatic identification of the ship is composed of Ramp-Up (RU) data, SyncWord (SW) data, Link Config Identity (LCID) data, Data Symbol (DS) data, Ramp-Down (RD) data, and Guard Time (GD) data.

[0014] The signal is arranged in the order of RU data, SW data, LCID data, DS data, RD data, and GD data. Each of the RU data, the SW data, the LCID data, the DS data, and the RD has a prescribed number of bits, and each is modulated by a prescribed modulation method. The prescribed modulation method may include but is not limited to Quadrature Phase Shift Keying (QPSK), 8 Phase-Shift Keying (PSK), 16 Quadrature amplitude modulation (QAM), etc.

[0015] RU data represents a beginning of data of the AIS ([Universal Shipborne] Automatic Identification System) signal. SW data is for timing detection and frequency control. LCID data represents a modulation method of DS data. DS data includes various information for the AIS 10 such as ship identification ID. RD data is for AIS signals, more specifically, data representing the end of DS data. The GD is a time interval left vacant, having no signal or data, during which no data is sent. The SW data corresponds to a "preamble" of the received signal.

[0016] FIG. 4 shows an example of a bit array of the SW data. As shown in FIG. 4, the SW data is composed of a non-inversion code 402 and an inversion code 404. The SW data is a sequence code of a non-inversion code and an inversion code. Specifically, the non-inversion code is, for example, a Barker code string of N = 13. The inversion code 404 is a code obtained by inverting the non-inversion code 402.

[0017] For example, the non-inversion code is "1, 1, 1, 1, 1, 0, 0, 1, 0, 0, 1, 0, 0, 1, 1, 0, 0, 0, 1, 0, 0, 1, 0, 0." Thus, SW data is "1, 1, 1, 1, 1, 1, 0, 0, 1, 1, 0, 1, 0, 0, 0, 0, 0, 1, 1, 0, 0, 1, 0, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0."

[0018] The coarse frequency control module 41 estimates and calculates the frequency deviation from the received signal to perform coarse frequency control. By the processing of the coarse frequency control module 41, for example, the frequency of the reference signal is driven from a range of + / - 500 Hz to a range of + / - 30 Hz relative to the frequency of the received signal.

[0019] The symbol timing detection module 42 detects symbol timing for the received signal after the coarse control output from the coarse frequency control module 41. The second down conversion module 43 down-converts the output signal of the symbol timing detection module 42 to the baseband frequency.

[0020] The phase control module 44 performs automatic phase control on the signal down-converted to the baseband (baseband signal).

[0021] The frequency tracking module 45 performs automatic phase control and automatic frequency control with higher accuracy on the baseband signal output from the phase control module 44. This forces the frequency of the reference signal from a range of + / - 500 Hz to a range of + / - 30 Hz relative to the frequency of the received signal. Therefore, convergence to the desired symbol point can be achieved with high accuracy. The frequency tracking module 45 outputs the signal (demodulated signal) after the automatic phase control and the automatic frequency control to the decoding module 60.

[0022] The signal detection module 51 detects the RU data of the received signal.

[0023] The correlation module 52 uses the timing of the RU data to perform correlation processing between the received signal and the reference code. The specific configuration and processing of the correlation module 52 will be described later. The correlation module 52 outputs the correlation processing result to the decoding module 60. The correlation processing result output from the correlation module 52 has a main lobe corresponding to the slot timing of the received signal. Therefore, the correlation result (output correlation result) output from the correlation module 52 enables the detection of the slot timing of the received signal. That is, the correlation module 52 corresponds to the "timing detection device 52" of the present invention.

[0024] Using the demodulation signal and the timing of detection of the main lobe of the correlation result (peak detection timing), the decoding module 60 decodes data including various information for an AIS such as a ship identification ID from the DS (Data Symbol) data.(Configuration and Processing of Correlation Module)

[0025] As shown in FIG. 1, the correlation module 52 includes a correlation processing module 521, a correlation processing module 522, a subtraction module 523, a VCO 524, a main reference code generation module 525, and an auxiliary reference code generation module 526. The correlation processing module 521 corresponds to the "first correlation processing module" of the present invention, and the correlation processing module 522 corresponds to the "second correlation processing module" of the present invention.

[0026] The VCO 524 generates a reference frequency signal for correlation processing. The VCO 524 outputs the reference frequency signal to a main reference code generation module 525 and an auxiliary reference code generation module 526.

[0027] FIG. 5A is a diagram showing an example of the bit arrangement of a main reference code C51 in accordance with a first embodiment of the present invention, and FIG. 5B is a diagram showing an example of the bit arrangement of an auxiliary reference code C52 in accordance with the first embodiment of the present invention.

[0028] The main reference code generation module 525 generates the main reference code C51 using the reference frequency signal. The main reference code generation module 525 outputs the generated main reference code C51 to the correlation processing module 521.

[0029] As shown in FIG. 5A, the main reference code C51 is a sequence code of a first code sequence C511 and a second code sequence C512. The first code sequence C511 is the same code as the non-inversion code of SW data. The second code sequence C512 is the same code as the inversion code of SW data. Specifically, in this embodiment, the first code sequence C511 is "1, 1, 1, 1, 1, 0, 0, 1, 0, 1, 0, 1, 0, 0, 1, 0, 1" and the second code sequence C512 is "0, 0, 0, 0, 0, 1, 0, 0, 1, 0, 0." Therefore, the main reference code C51 is "1, 1, 1, 1, 1, 1, 0, 0, 1, 1, 0, 1, 0, 0, 0, 0, 0, 1, 1, 0, 0, 1, 0, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0" and is the same code as SW data.

[0030] The auxiliary reference code generation module 526 generates the auxiliary reference code C52 using a reference frequency signal. The auxiliary reference code generation module 526 outputs the generated auxiliary reference code C52 to the correlation processing module 522.

[0031] As shown in FIG. 5B, the auxiliary reference code C52 is a sequence code of the first code sequence C511. The first code sequence C511 is the same code as the non-inversion code of the SW data. Specifically, in this embodiment, the first code sequence C511 is "1,1,1,1,1,1,0,0,1,1,0,1." Therefore, the auxiliary reference code C52 is "1, 1, 1, 1, 1, 1, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 1, 1, 0, 1, 1, 0, 1, 0, 1, 0, 1." That is, the auxiliary reference code C52 is constructed using a portion of the SW data, and more specifically, a non-inversion code of the SW data.

[0032] The first correlation processing module 521 performs correlation processing between the received signal and the main reference code C51, and outputs the absolute value data of the first correlation result (first correlation data) to the subtraction module 523.

[0033] The second correlation processing module 522 performs correlation processing between the received signal and the auxiliary reference code C52, and outputs the absolute value data of the second correlation result (second correlation data) to the subtraction module 523.

[0034] The subtraction module 523 differentiates the absolute value data of the first correlation result (first correlation data) from the absolute value data of the second correlation result (second correlation data), and outputs the final correlation result (final correlation data).

[0035] FIG. 6A and FIG. 6B show the correlation result (first correlation result) between the SW data and the main reference code C51, and FIG. 6C and FIG. 6D show the correlation result (second correlation result) between the SW data and the auxiliary reference code C52. FIG. 6B shows the absolute value data of FIG. 6A, and FIG. 6D shows the absolute value data of FIG. 6C.

[0036] As mentioned above, the SW data contains N = 26 bits and can have a longer code length than the Barker code string with N = 13. This can increase the ratio of the size of the peak produced in the correlation result to the size of the noise floor and achieve synchronization and frequency control with greater precision.

[0037] However, by using the Barker code sequence consecutively, the suppression effect of the side lobe, as when using the Barker code sequence alone, is reduced. Thus, as shown in FIG. 6A and FIG. 6B, the first correlation result (first correlation data), in which the correlation is performed using the main reference code C51 having the same code structure as the SW data, generates a sidelobe of a prescribed level together with the main lobe.

[0038] Here, the second correlation result (second correlation data), in which the correlation is performed using the auxiliary reference code having the above code structure, generates only a sidelobe as shown in FIG. 6C and FIG. 6D.

[0039] Moreover, by making the main reference code C51 and the auxiliary reference code C52 have the above code structure, the position of the side lobe (position on the time axis) of the correlation (first correlation result (first correlation data)) using the main reference code C51 and the position of the side lobe (position on the time axis) of the correlation (second correlation result (second correlation data)) using the auxiliary reference code C52 become the same.

[0040] Therefore, when the subtraction module 523 performs a difference operation between the first correlation result (first correlation data) and the second correlation result (second correlation data), the side lobes are canceled and suppressed, and only the main lobe remains.

[0041] FIG. 7 shows the final correlation result (final correlation data). As shown in FIG. 7, the final correlation result (final correlation data) has almost no side lobe and the main lobe remains.

[0042] Thus, by using the configuration and processing of this embodiment, the correlation module 52 (or the timing detection device) can suppress the side lobe during correlation processing. Thus, the AIS device 10 can perform synchronization with high accuracy. The AIS device 10 can also perform frequency control with high accuracy.(Timing Detection Method)

[0043] FIG. 8 is a flowchart showing an example of a timing detection method according to an embodiment of the present invention. In the specific content of each process of the flowchart shown in FIG. 8, each module described by the explanation of the above configuration is omitted from the description below.

[0044] At step S11 of the timing detection method, the correlation module 52 generates the main reference code C51, and the auxiliary reference code C52. At step S12 of the timing detection method, the correlation module 52 executes the first correlation using the main reference code C51 and the second correlation using the auxiliary reference code C52. At step S13 of the timing detection method, the correlation module 52 differentiates the first correlation result from the second correlation result.(Embodiment 2)

[0045] A timing detection technique according to a second embodiment of the present invention will be described with reference to the figures. FIG. 9A is a diagram showing an example of the bit arrangement of the main reference code C51 according to the second embodiment of the present invention, and FIG. 9B is a diagram showing an example of the bit arrangement of an auxiliary reference code C52A according to the second embodiment of the present invention. FIG. 10A and FIG. 10B are diagrams showing the correlation result (second correlation result) between SW data and the auxiliary reference code C52A. FIG. 10B is the absolute value data in FIG. 10A.

[0046] The timing detection technique of the second embodiment differs in the auxiliary reference code from the timing detection technique of the first embodiment. Other contents of the timing detection technique of the second embodiment are the same as those of the timing detection technique of the first embodiment, and each description of the same modules is omitted.

[0047] As shown in FIG. 9A, the correlation module 52 generates a code in which the first code sequence C511 and the second code sequence C512 continue as the main reference code C51. Therefore, the main reference code C51 is the same code as the SW data. The correlation module 52 uses the main reference code C51 to execute the first correlation.

[0048] As shown in FIG. 9B, the correlation module 52 generates a code in which the second code sequence C512 continues as the auxiliary reference code C52A. Specifically, in this embodiment, the auxiliary reference code C52A is "0, 0, 0, 0, 0, 1, 1, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0."

[0049] The correlation module 52 executes the second correlation using the auxiliary reference code C52A.

[0050] By using the auxiliary reference code C52A, as shown in FIG. 10A and FIG. 10B, in the second correlation result (the second correlation data), the main lobe is suppressed and the side lobe is generated without suppression.

[0051] Therefore, by using the auxiliary reference code C52A, the side lobe can be suppressed in the final correlation result (the final correlation data).(Embodiment 3)

[0052] A timing detection technique according to a third embodiment of the present invention will be described with reference to the figures. FIG. 11A is a diagram showing an example of the bit arrangement of the main reference code C51 according to the third embodiment, and FIG. 11B is a diagram showing an example of the bit arrangement of the auxiliary reference code C52B according to the third embodiment of the present invention. FIG. 12 is a diagram showing the final correlation result (final correlation data) according to the third embodiment.

[0053] The timing detection technique according to the third embodiment differs from the timing detection technique according to the second embodiment in the auxiliary reference code. The other contents of the timing detection technique according to the third embodiment are the same as those of the timing detection technique according to the second embodiment, and each description of the same modules is omitted.

[0054] As shown in FIG. 11A, the correlation module 52 generates a code in which the first code sequence C511 and the second code sequence C512 continue as the main reference code C51. Therefore, the main reference code C51 is the same code as the SW data. The correlation module 52 executes the first correlation using the main reference code C51.

[0055] As shown in FIG. 11B, in the correlation module 52, as the auxiliary reference code C52B, the second code sequence C512 and the third code sequence C512B sequentially generate codes. The third code sequence C512B is a code in which some bits of the second code sequence C512 are different. More specifically, the third code sequence C512B is a code in which the last bit of the second code sequence C512 is reversed.

[0056] More specifically, in this embodiment, the third code sequence C512B is "0, 0, 0, 0, 0, 1, 0, 0, 1, 1." Therefore, the auxiliary reference code C52B is "0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,1,0,1."

[0057] The correlation module 52 executes the second correlation using the auxiliary reference code C52B.

[0058] By using such auxiliary reference code C52B, as in the second embodiment, the main lobe is suppressed and the side lobe is generated with little suppression.

[0059] Therefore, as shown in FIG. 12, in the final correlation result (final correlation data), the main lobe is not suppressed and the side lobe can be suppressed.(Embodiment 4)

[0060] A timing detection technique according to a fourth embodiment of the present invention will be described with reference to the figures. FIG. 13A is a diagram showing an example of the bit arrangement of the main reference code C51 according to the fourth embodiment, and FIG. 13B is a diagram showing an example of the bit arrangement of an auxiliary reference code C52C according to the fourth embodiment. FIG. 14 is a diagram showing the final correlation result (final correlation data) according to the fourth embodiment.

[0061] The timing detection technique of the fourth embodiment differs in the auxiliary reference code from the timing detection technique of the second embodiment. Other contents of the timing detection technique of the fourth embodiment are the same as those of the timing detection technique of the second embodiment, and each description of the same modules is omitted.

[0062] As shown in FIG. 13A, the correlation module 52 generates a code in which the first code sequence C511 and the second code sequence C512 continue as the main reference code C51. Therefore, the main reference code C51 is the same code as the SW data. The correlation module 52 uses the main reference code C51 to execute the first correlation.

[0063] As shown in FIG. 13B, in the correlation module 52, as the auxiliary reference code C52B, the second code sequence C512 and a fourth code sequence C512C sequentially generate codes. The fourth code sequence C512C is a code in which some bits of the second code sequence C512 are different. More specifically, the fourth code sequence C512C is a code in which the first bit of the second code sequence C512 is reversed.

[0064] Specifically, in this embodiment, the fourth code sequence C512C is "1, 0, 0, 0, 0, 1, 1, 0, 0, 1, 0, 1, 0." Therefore, the auxiliary reference code C52B is "0, 0, 0, 0, 0, 1, 1, 0, 0, 1, 0, 1, 0, 1, 0, 0, 0, 0, 1, 1, 0, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 0."

[0065] The correlation module 52 executes the second correlation using the auxiliary reference code C52C.

[0066] By using such an auxiliary reference code C52C, as in the second embodiment, the main lobe is suppressed and the side lobe is generated with little suppression.

[0067] Therefore, as shown in FIG. 14, in the final correlation result (final correlation data), the main lobe is not suppressed and the side lobe can be suppressed.

Claims

1. A timing detection device (52), comprising: a main reference code generation module (525) configured to generate a main reference code (C51) consisting of the same code as a code for synchronization included in a received signal; an auxiliary reference code generation module (526) by using a portion of the same code as the code for synchronization, configured to generate an auxiliary reference code (C52; C52A; C52B; C52C) consisting of a code configuration different from the main reference code (C51) so as to suppress the generation of a main lobe in a second correlation result during a correlation process between the received signal and the auxiliary reference code; a first correlation processing module (521) configured to output a first correlation result by correlating the received signal with the main reference code (C51); a second correlation processing module (522) configured to output the second correlation result by correlating the received signal with the auxiliary reference code (C52; C52A; C52B; C52C); and a subtraction module (523) configured to subtract the first correlation result from the second correlation result, wherein the code for synchronization is composed of a first code sequence (C511) of a non-inversion code consisting of a prescribed spread code and an inversion code of the spread code, and the auxiliary reference code generation module (526) is further configured to generate the auxiliary reference code (C52) using the first code sequence (C511) of the non-inversion code.

2. The timing detection device (52) according to claim 1, wherein the auxiliary reference code (C52) is a sequence code of the non-inversion code.

3. The timing detection device (52) according to any of claim 1 or 2, wherein the code for synchronization is a Barker code.

4. A timing detection method, comprising: generating a main reference code (C51) consisting of the same code as a code for synchronization included in a received signal; generating an auxiliary reference code (C52; C52A; C52B; C52C) consisting of a code configuration different from the main reference code (C51) by using a portion of the same code as the code for synchronization so as to suppress generation of a main lobe in a second correlation result during a correlation process between the received signal and the auxiliary reference code; outputting a first correlation result by correlating the received signal with the main reference code (C51); outputting the second correlation result by correlating the received signal with the auxiliary reference code (C52; C52A; C52B; C52C); and subtracting the first correlation result from the second correlation result, wherein the code for synchronization is composed of a sequence code of a non-inversion code consisting of a prescribed spread code and an inversion code of the spread code, and the auxiliary reference code (C52) is generated using the sequence code of the non-inversion codes.

5. The timing detection method according to claim 4, wherein the auxiliary reference code (C52) is the sequence code of the non-inversion code.

6. The timing detection method according to any of claim 4 or 5, wherein the code for synchronization is a Barker code.

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